feat: добавить лестницы между этажами (#663)

Прямые и винтовые лестницы получили отдельную модель, инструменты редактора, безопасную межэтажную навигацию, вычитание из чистой площади и плоское отображение в 2.5D.

Issue: #663
User-Visible: yes

docs/ARCHITECTURE.md

@@ -26,6 +26,11 @@ houseplan-card/
 │  ├─ houseplan-panel.ts         # HA sidebar/app-bar host for the same full card
 │  ├─ editor-runtime-loader.ts   # lazy loader: dedupe, retry and build handshake
 │  ├─ houseplan-editor-runtime.ts # Plan/Devices/Background composition root
+│  ├─ stairs-view.ts             # eager read-only stair symbols, links and gesture guards
+│  ├─ stairs-editor.ts           # lazy Plan stair tools, transforms and properties
+│  ├─ stairs-editor-model.ts     # pure editor transforms, snapping and target-state helpers
+│  ├─ stairs.ts                  # stair model, render geometry and area math
+│  ├─ clean-floor.ts             # shared room-floor subtraction including stair footprints
 │  ├─ decor-image-editor.ts      # lazy Background/Furniture image palette, upload and properties controller
 │  ├─ houseplan-onboarding-runtime.ts # first-space/import dialogs, independent of editor
 │  ├─ iso-scene-render.ts        # lazy 2.5D scene/runtime boundary (settings.volumetric_view, #649)
@@ -656,7 +661,7 @@ not be added to an individual sink.
                "rooms":[{"id","name","area","poly|x/y/w/h","wall_ids":[…],"settings"}],
                "wall_segments":[{"id","a","b","cm","owners":[…]}],
                "partitions":[…], "wall_columns":[…],
-               "openings":[…], "decor":[…], "settings":{…} }],
+               "openings":[…], "decor":[…], "stairs":[…], "settings":{…} }],
   "markers": [{ "id","binding":"device:<id>|entity:<eid>|virtual","hidden","removed",
                 "name","icon","display","controls","is_light","glow_color","tap_action",
                 "room_id","pdfs",… }],
@@ -940,7 +945,7 @@ designer handoff are attached to issue #570.
 ## Markup editor (v1.4.0+)
 
 State inside the card: `_markup` (mode), `_tool` (draw/column/merge/split/resize/opening/
-wallthick/delroom), `_path` (the current outline,
+stairs/wallthick/delroom), `_path` (the current outline,
 vertices on the GRID_N=240 grid). Clicks on the stage → `_svgPoint`→`_snap`. The outline is closed
 = a click on the first vertex → area select (hass.areas) + name → room {poly}. Polygon rooms and
 rectangles are rendered uniformly (hit-test: point-in-polygon / rect).
@@ -1125,6 +1130,28 @@ While drawing, the length of the current segment follows the cursor (`_fmtLen`
 per-space `cell_cm` — canonical centimetres represented by one grid cell; new
 spaces use 1 cm or 2.54 cm/1 inch, while missing legacy values fall back to 5 cm.
 
+### Stairs (#663)
+
+Stairs are a separate Plan entity, not decor. The lazy `StairEditorRuntime`
+owns the straight/spiral tool group, selection, continuous
+move/resize/rotation, wall/stair magnet and properties. The eager
+`StairViewRuntime` owns only read-only symbols, guarded navigation and gesture
+suppression, so opening a plan does not load the editor graph. The root card
+owns lifecycle composition, shared Plan history/persistence and stage pointer
+terminals. `stairs.ts` is the pure boundary for the discriminated model, exact
+30 cm tread geometry, cached render projection and footprint containment;
+`stairs-editor-model.ts` contains the pure transform, target-state and
+footprint-to-footprint snapping helpers used by the editor.
+
+`spaces[].stairs[]` is optional and capped at 250 records. A record exists on
+one space only; `target_space_id` is a one-way navigation reference and never
+creates target geometry. Straight footprints are rotated rectangles; spiral
+footprints are circles. `clean-floor.ts` subtracts their geometric overlap
+from the same clean-area result used by room cards and summary metrics, without
+cutting the painted floor or changing walls/light/vacuum. PDF and full/static
+renderers consume the same stair geometry. The 2.5D scene keeps the SVG object
+on its floor plane with no height or shadow. See `docs/STAIRS.md`.
+
 ## Editor chrome and contextual controls
 
 Every editor uses one stable primary `.editbar`. Its `.editbar-tools` contains

docs/CANVAS.md

@@ -16,7 +16,7 @@ coordinate system.
 
 ## Principle
 
-1. **Coordinates keep their meaning.** Rooms, openings, decor and
+1. **Coordinates keep their meaning.** Rooms, openings, decor, stairs and
    device positions are still stored normalised. `1.0` is still the
    same distance it always was; `cell_cm` still ties a grid cell to
    real centimetres. **No data migration.** An existing plan opens as
@@ -56,8 +56,10 @@ Negative zero becomes positive zero.
 
 The lattice allow-list covers room outlines/extents, exact wall endpoints,
 opening `x/y`, decor origins/sizes/endpoints, drafts, partitions, columns, open
-spans and layout `x/y`. Angles, opening length/host `t`, decor scale and
-backdrop transforms retain the nine-decimal scalar contract. The traversal
+spans and layout `x/y`. Angles, opening length/host `t`, decor scale, backdrop
+transforms and every stair transform field retain the nine-decimal scalar
+contract. Stairs are deliberately excluded even when a value is near a grid
+node: their continuous wall-face magnet position is authored data. The traversal
 deliberately excludes `cell_cm`, `plan_aspect`, `view_box`,
 physical centimetre fields, colours/opacities/live values, presentation scales
 and vacuum affine calibration. Unknown/future numeric fields round-trip
@@ -113,6 +115,7 @@ the exact target atomically without exposing a default-fit frame.
 | `_GEOM` (room x/y, poly points, opening x/y, `view_box` origin) | `-4 .. 4` | `-5000 .. 5000` | coordinate |
 | `_EXTENT` (room w/h, `view_box` w/h) | `0.001 .. 4` | `0.001 .. 5000` | size — strictly positive |
 | `_NORM` (decor x/y/w/h) | `-1 .. 2` | `-5000 .. 5000` | coordinate |
+| stair `x/y`, `length/width/radius` | — | `-5000 .. 5000`; sizes positive | continuous transform |
 | opening `length` | `0.001 .. 1` | `0.001 .. 5000` | size — strictly positive |
 
 `+/-5000` is **garbage insurance, not a frame**. At the historical compatibility
@@ -132,6 +135,7 @@ tested. Input is a list of **items**, one per drawn/placed object:
 * the backdrop image rectangle, when the space has one;
 * every opening (door/window/gate) end-to-end segment;
 * every decor shape;
+* every stair, using its complete rotated rectangle or circular footprint;
 * every device the layout actually places in this space **and that the card
   actually draws** — a HIDDEN device (docs/FILTERING.md) is not content: the
   frame is presentation, and an object nobody can see must not decide what the
@@ -276,7 +280,7 @@ produce a zero-sized SVG `viewBox`.
   in the decision — `_clampView` alone says how far you may walk.
 * **Who owns the pointer.** A drag pans only when it starts on empty
   scene: the room-resize handles, device badges, openings, room labels
-  and the decor shapes take the pointer first (`_stagePointerDown`
+  stairs and the decor shapes take the pointer first (`_stagePointerDown`
   bails out on them), and a drawing tool that consumes the press —
   decor line/rect/ellipse/text — bails out too. Two fingers are always
   a pinch, never a pan. On a **kiosk** screen at swipe zoom (`≤ 1`,
@@ -526,10 +530,18 @@ exception to positional quantisation: it is continuous in both modes, with
 Shift selecting independent axes, while Shift on its rotation handle snaps to
 45°. Furniture placement and movement remain grid-bound.
 
+Stairs use the continuous branch of this contract for their complete
+transform. Move and resize stay off-grid when authored there; Shift snaps only
+rotation to 45°. Wall magnet resolves the visible physical face (including
+half-thickness) and stair magnet resolves outer footprint-to-footprint contact.
+Neither save/load nor Optimize may replace that contact with a nearby lattice
+node.
+
 ### 9.5 «Оптимизировать планы» — explicit whole-plan maintenance
 
-Existing and imported plans may still hold coordinates between the
-nodes. New editor operations cannot create more. General settings contain
+Existing and imported plans may still hold grid-bound coordinates between the
+nodes. Ordinary grid-bound editor operations do not create more; explicitly
+continuous objects are exempt. General settings contain
 a **Plan maintenance** group whose action previews and then repairs old
 data through all current passes: model upgrades, mandatory grid
 alignment, exact open-span canonicalisation and wall-interval compaction.
@@ -585,9 +597,9 @@ either store changes, commits both revisions, and retains one snapshot.
 has changed since the optimization. A crash between store writes is
 completed from the intent on the next integration setup.
 
-The grid pass deliberately excludes the complete transform of `furniture` and
-uploaded `image` decor. Their position, size and rotation are continuously
-authored values (#383), so changing even one of those fields would make
+The grid pass deliberately excludes the complete transform of `furniture`,
+uploaded `image` decor and `spaces[].stairs[]`. Their position, size and
+rotation are continuously authored values (#383, #663), so changing even one of those fields would make
 Optimize create debt from a normal editor operation. Other decor kinds and
 storage-level numeric canonicalization keep their existing grid contract
 (#477).

docs/CHANGELOG.md

@@ -2,6 +2,16 @@
 
 ## Unreleased
 
+- The Plan editor can now place straight and one-turn spiral stair objects with
+  physical sizes, automatic 30 cm treads and an ascent arrow. Stairs move,
+  resize, rotate and snap continuously to wall faces or each other; their
+  footprint is deducted from clean room area without cutting the visible
+  floor. An optional one-way target turns a stair into safe floor navigation
+  in View, while gestures, broken targets and fixed-floor cards remain inert.
+  The target floor is never changed automatically, and the first 2.5D version
+  stays flat on the floor plane
+  ([#663](https://github.com/Matysh/houseplan-card/issues/663)).
+
 ## v1.78.0-beta.5 — 2026-09-26
 
 - In the 2.5D plan the metrics row under a room name (temperature, humidity,
@@ -22,7 +32,6 @@
   footer button as the only clickable control. The regression came with the
   overlapping-marker fix in v1.76.0-beta.2
   ([#664](https://github.com/Matysh/houseplan-card/issues/664)).
-
 ## v1.78.0-beta.4 — 2026-09-26
 
 - The main toolbar is steadier and more compact: its editor close **×** now

docs/CHANGELOG.ru.md

@@ -8,6 +8,17 @@
 
 ## Не выпущено
 
+- В редакторе плана появились отдельные прямые и винтовые лестницы с физическими
+  размерами, автоматическим шагом ступеней 30 см и стрелкой подъёма. Лестницу
+  можно плавно перемещать, менять её размер, поворачивать и магнитить к грани
+  стены или другой лестнице; её габарит вычитается из чистой площади комнаты,
+  но не вырезает видимый пол. Необязательная односторонняя ссылка безопасно
+  переводит на выбранный этаж в Просмотре, а после жеста, при битой ссылке и в
+  карточке с закреплённым этажом переход не срабатывает. Целевой этаж
+  автоматически не меняется; в первой версии 2.5D лестница остаётся плоской
+  на полу
+  ([#663](https://github.com/Matysh/houseplan-card/issues/663)).
+
 ## v1.78.0-beta.5 — 2026-09-26
 
 - На объёмном плане (2.5D) строка показателей под названием комнаты
@@ -28,7 +39,6 @@
   единственный кликабельный элемент — кнопка в подвале. Регрессия пришла с
   исправлением перекрытий маркеров в v1.76.0-beta.2
   ([#664](https://github.com/Matysh/houseplan-card/issues/664)).
-
 ## v1.78.0-beta.4 — 2026-09-26
 
 - Основная панель стала компактнее и перестала дёргаться: крестик **×**

docs/CONFIG-COMPATIBILITY.md

@@ -112,6 +112,28 @@ An older frontend ignores the field and shows Flat. An older backend preserves
 it through the unknown-settings policy. Full backup/import carries `settings`
 whole, so the value survives.
 
+## Stairs (#663)
+
+`spaces[].stairs[]` is an optional bounded (250 records per space)
+discriminated collection. `kind: "straight"` stores positive `length` and
+`width` plus `direction: "forward" | "backward"`; `kind: "spiral"` stores a
+positive `radius` plus `direction: "clockwise" | "counterclockwise"`. Both
+variants carry stable `id`, continuous normalized centre `x/y`, scalar
+`angle`, and an optional nullable `target_space_id`.
+
+Stair transforms follow furniture's continuous contract. Config writes apply
+only the nine-decimal scalar cleanup to position, size and angle; they do not
+use near-lattice snapping, and Optimize does not move them. Full backup,
+support data and diagnostics retain the bounded records. Full import remaps a
+known target space id and clears a target that was not imported; single-space
+transfer cannot invent a link to an external floor. Deleting a target space
+clears incoming links without deleting the source stair.
+
+The collection is additive and requires no model/store version migration. A
+current frontend renders and edits it; a legacy frontend ignores the objects.
+The current backend preserves valid records through unrelated writes, while a
+backend predating the field must not be used to edit a newer configuration.
+
 ## Sun-ray window face (#577)
 
 `settings.sun_ray_origin` is an optional global enum: `inner` or `outer`.

docs/ISOMETRIC.md

@@ -92,7 +92,7 @@ Composition remains SVG-first:
 3. screen-facing HTML overlays.
 
 The floor keeps the same nodes and order for paper/backdrop, room fills/hover,
-Glow/spill, sun, decor/furniture, opening symbols and vacuum path/outline. Stage
+Glow/spill, sun, decor/furniture, flat stair symbols, opening symbols and vacuum path/outline. Stage
 1 does not add a second light source/layer. Markers and room cards intentionally
 remain above walls without geometric occlusion.
 
@@ -248,7 +248,7 @@ search. There is no painted plate, long tether, ground dot or per-marker
 shadow. The original screen-facing HTML root remains the only hit, focus,
 tooltip and action target, and selection/hover cannot invalidate the placement
 cache. Vacuum, Glow/spill, SUN, room fills/hover, arbitrary decor,
-furniture/backdrop and every persisted coordinate remain on `z=0`.
+furniture/backdrop, stairs and every persisted coordinate remain on `z=0`.
 
 Room names remain screen-facing and lose stroke, text shadow, drop shadow and
 halo. Iso uses `#303936` on a light presentation and `#f2f0e8` on a dark one;

docs/README.ru.md

@@ -11,6 +11,7 @@
 | [Полное руководство пользователя](USER-GUIDE.ru.md) | Пользователи и администраторы Home Assistant | Установка, первая настройка, пространства, комнаты, стены, проёмы, устройства, визуальные состояния, заливки, подложка, солнце, пылесосы, киоск, обслуживание и диагностика |
 | [Радары присутствия](RADAR.md) | Пользователи, администраторы и интеграторы | Поддерживаемые профили, привязка источников, установка и калибровка, статусы данных, приватность и диагностика |
 | [Редактор подложки и декора](DECOR-EDITOR.md) | Пользователи, тестировщики и разработчики | Инструменты, единое выделение и трансформации, физические размеры, магнит, Undo/Redo, поведение картинки-подложки и совместимость старых полей |
+| [Лестницы и переходы между этажами](STAIRS.md) | Пользователи, тестировщики и разработчики | Прямые и винтовые лестницы, размеры, направление подъёма, магнит, связь этажей, площадь и ограничения 2.5D |
 | [GitHub Issues](https://github.com/Matysh/houseplan-card/issues) и [Project v2](https://github.com/users/Matysh/projects/1) | Владелец, разработчики и контрибьюторы | Единственный актуальный backlog: задачи, приоритеты, решения и статусы выполнения |
 
 Старые тематические документы в этом каталоге остаются инженерными спецификациями и историей решений. При расхождении пользовательского описания с интерфейсом текущей версии приоритет имеет новое руководство, а при расхождении с фактическим поведением — код текущей версии.

docs/STAIRS.md

@@ -0,0 +1,93 @@
+# Stairs
+
+Stairs are plan-level navigation objects. They show the physical place and
+direction of an ascent on one space and can link that space to one other House
+Plan space. The link is deliberately one-way: adding or editing a stair never
+creates or changes anything on the target floor.
+
+## User contract
+
+The Plan editor has one **Stairs** group with **Straight** and **Spiral** tools.
+A click places the chosen default; the object remains selected. Drag moves it,
+the visible handles resize it, and the upper handle rotates it. Straight stairs
+have corner and one-axis edge handles. A spiral stair remains a circle and has
+one radial resize handle. Rotation is continuous; holding `Shift` snaps to the
+nearest multiple of 45 degrees. `Esc` cancels an active transform or clears the
+selection; Delete/Backspace removes the selected stair; the ordinary Plan
+Undo/Redo history covers create, edit, transform and delete.
+
+Double click opens properties. A straight stair stores positive length and
+width; a spiral stair stores a positive radius. The dialog also selects the
+rise direction, rotation and an optional target space. A target cannot be the
+current space. A missing, self or deleted target leaves the stair visible and
+editable but shows a repair warning and makes View activation a no-op.
+
+In an ordinary multi-space card, a clean click/tap or keyboard activation on a
+valid stair switches to the target tab and restores that floor's remembered
+camera. Pan, pinch, long press, swipe and pointer cancellation do not navigate.
+In a card configured with `floor`, stairs are visible but inert. The target
+floor receives no automatic stair, highlight or camera centring.
+
+## Geometry and drawing
+
+Both variants use the same continuous transform contract as furniture: their
+authored position, size and angle are not grid-quantised on save or by
+**Optimize plans**. A stair near a wall snaps to the visible physical wall face;
+a straight stair also becomes parallel to that face. Any straight/circular pair
+of stairs can snap footprint-to-footprint. The other stair is never modified or
+linked by the magnet.
+
+Straight tread lines are perpendicular to the rise axis and start at the lower
+edge every 30 cm. A remainder shorter than 30 cm stays at the upper edge.
+Spiral stairs make one full turn; radial treads use the same 30 cm physical step
+measured on the travel line at two thirds of the radius. Their direction is
+clockwise or counter-clockwise when viewed from above. The arrow always means
+physical ascent, not the direction of navigation between named tabs.
+
+The footprint overlap is removed from clean room floor area exactly once. It
+does not cut the visible floor, change room or wall geometry, create a light
+occluder, affect Glow/sun/vacuum, or participate in Optimize. In 2.5D the first
+version remains a flat symbol projected with the floor/decor plane; it has no
+height, risers, railings or shadows.
+
+## Persisted model
+
+Each space may contain `stairs: []`, bounded to 250 valid records:
+
+```json
+{
+  "id": "stair-main",
+  "kind": "straight",
+  "x": 0.42,
+  "y": 0.55,
+  "angle": 90,
+  "length": 0.24,
+  "width": 0.10,
+  "direction": "forward",
+  "target_space_id": "floor-2"
+}
+```
+
+`kind:"spiral"` replaces `length`/`width` with `radius` and uses direction
+`clockwise` or `counterclockwise`. Coordinates and sizes use the normalized
+plan coordinate system; physical labels are derived through `cell_cm`.
+`target_space_id` is nullable. Unknown sibling fields survive validation and
+round trips for forward compatibility. Full backup/import/export, one-space
+transfer, plan-only transfer, diagnostics and support packages preserve the
+same records. When a complete backup removes a target space its incoming stair
+links are cleared; a one-space transfer cannot invent an external target.
+
+## Implementation boundary
+
+- `src/stairs.ts` owns validation, drawing geometry and area-subtraction
+  primitives.
+- `src/stairs-view.ts` is the eager read-only boundary for symbols, guarded
+  navigation and touch/pointer gesture suppression.
+- `src/stairs-editor-model.ts` owns pure Plan transforms, target state and
+  stair-to-stair magnet math; `src/stairs-editor.ts` owns the lazy Plan UI and
+  properties.
+- `src/clean-floor.ts` and `src/summary-panel-metrics.ts` consume the same
+  footprint subtraction for room cards and summary totals; PDF rendering uses
+  the same stair outline/tread geometry without changing the room floor paint.
+- Backend schemas and transfer/support surfaces treat `stairs` as a bounded,
+  additive space collection. Old configs without it remain unchanged.

docs/STYLING-HOOKS.md

@@ -98,6 +98,7 @@ Everything in this table is **public API**.
 | Wall body (thickness) | `path` (SVG) | `wall` | `data-id` = segment key, `data-kind` = `shared` \| `outer` | `.wallbody` |
 | Independent partition | `path` (SVG editor hit target) | `partition` | `data-id` = partition id, `data-kind` = `partition` | `.physical-hit` |
 | Wall column | `path` / `circle` (SVG editor hit target) | `wall-column` | `data-id` = column id, `data-kind` = `square` \| `circle` | `.physical-hit` |
+| Stair | `g` (SVG) | `stair` | `data-id` = stair id, `data-kind` = `straight` \| `spiral`, `data-target-state` = `active` \| `missing` \| `self` \| `deleted` \| `fixed` | `.hp-stair` |
 | Decor shape | `line` / `rect` / `ellipse` / `text` (SVG) | `decor` | `data-id` = shape id, `data-kind` = `line` \| `rect` \| `ellipse` \| `text` | `.dshape` (`.dtext` on text); persisted colour/alpha are inline SVG attributes and therefore win over weak CSS selectors |
 | Furniture | `path` (SVG) | `decor` | `data-id` = shape id, `data-kind` = `furniture`, `data-symbol` = the symbol id (`sofa`, `toilet`, …) | `.dshape .dfurn` |
 | Floor / space tab | `button` (HTML, header) | `space-tab` | `data-id` = space id | `.tab` |

docs/TOUCH-SUPPORT.md

@@ -37,6 +37,8 @@ On phones, tablets, wall panels and HA Companion apps, the ordinary View must:
   tabs, zoom and one gear whose menu holds every other header action, each
   item a 44 px target (#616);
 - support convenient pan, pinch zoom and space switching;
+- treat a linked stair as a floor-navigation target only after a clean tap;
+  pan, pinch, long press, swipe and cancellation tails must stay inert;
 - fit the whole plan after two clean taps on free scene background, while one
   tap on a room keeps the immediate room-fit action;
 - provide a touch path for essential information that desktop exposes through
@@ -158,6 +160,11 @@ Desktop `Shift` bypasses that offer and constrains drawing to an exact 45° ray;
 touch has no separate modifier gesture. A pan, pinch, cancellation or second
 pointer never accepts a face, applies a small-gap repair or creates a room.
 
+Stair placement and transforms remain best-effort editor interactions on
+touch, but the safety floor is strict: cancellation and navigation gestures do
+not create, move, save or follow a stair. A long press in View does not activate
+its target floor, and the next deliberate tap is re-armed immediately.
+
 During a View/editor visual transition the moving stage is inert while the
 header tabs remain available. A pinch, cancelled pointer or synthetic click
 cannot operate stale geometry; leaving the editor is always a single safe

docs/USER-GUIDE.md

@@ -594,6 +594,7 @@ shape change it is retained only while it remains inside the room.
 | Walls | Continuous wall chain; offers rooms when it closes faces and finishes open chains as independent walls | Only a confirmed room has area | Positive thickness blocks light; zero thickness follows the space's dashed/solid policy | Partial room overlap is rejected; there is no separate Partition or Boundary drawing tool |
 | Column | Square or circular support | Does not change area | Blocks light inside its shape | One shape/size/rotation; not a wall or room |
 | Opening | Door, window or gate | Does not change area | Door/gate passage follows state; window may cast sun | Must fit completely on a suitable wall segment |
+| Stairs | Straight flight or one-turn spiral with automatic 30 cm treads and an ascent arrow | Subtracts only its footprint overlap from clean area | No effect on Glow, sun or walls | Lives on this floor only; a valid optional target makes it a View link |
 
 Other operations edit existing geometry:
 
@@ -605,6 +606,16 @@ Other operations edit existing geometry:
 | Thickness | Changes one span or every wall of a room, including zero-thickness walls |
 | Delete room | Deletes the room after choosing whether its exclusive physical walls remain; shared walls always remain |
 
+Choose **Stairs → Straight** or **Stairs → Spiral**, then click the plan. A
+selected stair moves and resizes smoothly like furniture; `Shift` snaps its
+rotation to 45°. It snaps to the visible physical face of a wall or flush to
+another stair, and **Optimize plans** preserves that exact continuous
+transform. Double click opens size, direction, angle and target-floor
+properties. In View a clean activation switches to the valid target and
+restores that floor's saved view; gesture tails, broken links and fixed-floor
+cards do nothing. The target floor is never changed automatically. In 2.5D the
+symbol is flat on the floor. See [Stairs](STAIRS.md).
+
 ![Selected partition and its Plan context tray](images/05-plan-context-tray.png)
 
 Deleting a room also clears that exact room from direct device assignments and

docs/USER-GUIDE.ru.md

@@ -779,6 +779,7 @@ Undo оптимизации.
 | Стены | Непрерывную цепочку стен; при замыкании предлагает комнаты, при выходе сохраняет независимые стены | Площадь появляется только у подтверждённой комнаты | Положительная толщина блокирует свет; нулевая следует настройке пространства | Частичное перекрытие комнат запрещено; отдельных инструментов «Перегородка» и «Граница» нет |
 | Колонна | Квадратную или круглую опору | Не меняет площадь комнаты | Блокирует свет внутри своей формы | Имеет одну форму/размер/поворот, но не является стеной или комнатой |
 | Проём | Дверь, окно, открытый проём или ворота на стене комнаты либо законченном независимом отрезке | Не меняет площадь | Дверь/ворота пропускают свет между полами, открытый проём — всегда; только наружное окно комнаты может давать солнечный луч | Должен целиком помещаться на одном подходящем отрезке стены |
+| Лестница | Прямой марш или один оборот винтовой лестницы с автоматическим шагом ступеней 30 см и стрелкой подъёма | Вычитает из чистой площади только пересечение своего габарита | Не влияет на Glow, солнце и стены | Существует только на этом этаже; необязательная корректная цель превращает её в ссылку в Просмотре |
 
 Остальные операции меняют уже созданную геометрию:
 
@@ -790,6 +791,17 @@ Undo оптимизации.
 | Толщина | Задаёт толщину 0–100 см выбранному участку или всем стенам комнаты |
 | Удалить комнату | Открывает выбор: удалить комнату и оставить её физические стены либо удалить комнату вместе с ними; общие стены остаются всегда |
 
+Выберите **Лестница → Прямая** или **Лестница → Винтовая**, затем кликните по
+плану. Выбранная лестница перемещается и меняет размер плавно, как мебель;
+`Shift` привязывает поворот к 45°. Магнит ставит её к видимой физической грани
+стены или вплотную к другой лестнице, а **Оптимизировать планы** сохраняет этот
+continuous-transform без привязки к сетке. Двойной клик открывает размеры,
+направление подъёма, угол и целевой этаж. В Просмотре чистый клик переходит на
+корректную цель и восстанавливает сохранённый вид этажа; хвост жеста, битая
+ссылка и карточка с закреплённым этажом ничего не делают. На целевом этаже
+объект автоматически не создаётся. В 2.5D символ остаётся плоским на полу.
+Подробный контракт — в [документе о лестницах](STAIRS.md).
+
 При варианте **«Удалить комнату, оставить стены»** эксклюзивные участки
 положительной толщины становятся обычными независимыми перегородками с той же
 толщиной, а их двери/окна перепривязываются к ним. Нулевые участки сохраняются

docs/UX-MODES.md

@@ -269,6 +269,11 @@ layer you cannot see is a layer you cannot edit.
 - Door, window, gate and passage may be hosted by one finished independent wall
   segment. Drafts and columns are never opening targets. Missing hosts fail
   dark and expose a rebind action only in Plan.
+- **Stairs** places a straight flight or a one-turn spiral as a separate Plan
+  object. It uses furniture-like continuous move/resize/rotation and physical
+  wall/stair magnet rather than the grid-bound wall contract. Its optional
+  one-way target is edited in properties; in View only a clean activation of a
+  valid target switches floors. The target floor is never modified.
 - **Select** is the only mode in which these objects intercept input. It offers
   rigid grid-bound drag, double-click/tap properties, Delete, and a rotate
   handle for square columns (5° steps; Shift is free). Draft Delete removes the

docs/data-hp-contract.json

@@ -43,6 +43,7 @@
           "rules",
           "settings",
           "space",
+          "stairs",
           "summary",
           "support",
           "vacuum"
@@ -156,6 +157,11 @@
       "since": "1.59.0-beta.3",
       "audience": ["styling", "test"]
     },
+    "stair": {
+      "elements": ["g"],
+      "since": "1.78.0-beta.5",
+      "audience": ["styling", "test"]
+    },
     "support": {
       "elements": ["button"],
       "since": "1.73.0-beta.7",
@@ -193,6 +199,7 @@
           "resize",
           "select",
           "split",
+          "stairs",
           "text",
           "wall-thickness"
         ]

docs/images/screenshots.json

@@ -3,7 +3,7 @@
   "fixture": "synthetic-only",
   "chromium": "151.0.7922.34",
   "oxipng": null,
-  "sourceFingerprint": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+  "sourceFingerprint": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
   "captureScriptSha256": "e2d14d89de793011615662af7c83c433768d4761f6cec7f0b3860c797494299e",
   "command": "npm run build && node demo/docs/capture.mjs",
   "scenarios": {
@@ -15,7 +15,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "1bde1bff8d4ab5f197320b54ef57186b3c07cf2121d5414ada63ce357826bfa8"
     },
     "view-touch": {
@@ -26,7 +26,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "f9dd5b54f86b814c00bc84149af84485f052b103cdcc9263b5c50bf5d32c69d6"
     },
     "space-create": {
@@ -37,7 +37,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "aab4811bba3afa6cc849cb9d3989d126b8c327b69a2f8f853e55fc077e0e9a1b"
     },
     "room-contour-close": {
@@ -48,7 +48,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "e106ff9db6c96adb08beba12cc299a88ac5fa47c079be316f185e5657bc656f0"
     },
     "plan-context-tray": {
@@ -59,7 +59,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "9b0db923fa7c8aff783b5c7050ee5b410b1b04df81a9e48bbc8111a7d0d47e76"
     },
     "device-editor": {
@@ -70,7 +70,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "198c084c0a45aa3afdf79181b80d8bb0347c95f3248b4fac9e05d69eb8a35f8f"
     },
     "device-display-preview": {
@@ -81,7 +81,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "e9b88d65dca74133646aa849d47bc09ad85eb8b16a168c4df6930e8f5856b5f5"
     },
     "background-editor": {
@@ -92,7 +92,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "44beadd61365ac1730c1efde846e528bfe92d8935fd167f1b6bf3bbad6af8f33"
     },
     "room-card": {
@@ -103,7 +103,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "d47988b03e6a078508b27b5612b6eafe8ecc33c891b589ddda1cc7c71f43b7c8"
     },
     "device-info": {
@@ -114,7 +114,7 @@
       },
       "theme": "dark",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "4ec8c6df671742b90ca55222917076c47c5035a6df0587282e60873c0ce5f64e"
     },
     "pdf-export": {
@@ -125,7 +125,7 @@
       },
       "theme": "light",
       "language": "en",
-      "sourceSha256": "25eae6908d0b7e5b154910505e483bc772e2f0406fed852c21b6ee910808a383",
+      "sourceSha256": "fcc2617295be1d37facbd00dea5df81fc5d3d11605b97f23da563a25df22425e",
       "imageSha256": "ad3d735135b180ce015c9cda07fdcec08d7c8707abe0665734ef7b450a8a7093"
     }
   },